The invention relates to a 2-component polyurethane sealants, in particular for the direct glazing of motor vehicles, comprising (A) a pasty polyurethane component containing a polyurethane prepolymer having free isocyanate groups, and a curing agent, and (B) a pasty component. Two-component sealants have been disclosed in GB-A-1,104,831 and EP-A-371,370, the curing agent being liberated by water and component (B) containing water as an essential constituent.
A fundamental problem of previous sealants is that, on the one hand, the processing or pot time must be sufficiently long to ensure flawless processing of the sealant before it cures, but, on the other hand, the curing must, for obvious reasons, take place as rapidly as possible when processing is complete. Finally, the polyurethane component (A) must also have an adequate shelf life.
Although previous 2-component polyurethane sealants mentioned at the outset have sufficient strength, for example, one hour after mixing, the processing time is, however, too short, which means problems can arise even during mixing of components (A) and (B) due to premature gelling of the sealants.